[IPV6] sit: Add missing MODULE_LICENSE

This is missing the MODULE_LICENSE statements and taints the kernel
upon loading. License is obvious from the beginning of the file.
Signed-off-by: Jan Dittmer <jdi@l4x.org>
Signed-off-by: Joerg Roedel <joro-lkml@zlug.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/sit.c

@@ -853,3 +853,4 @@ int __init sit_init(void)
 
 module_init(sit_init);
 module_exit(sit_cleanup);
+MODULE_LICENSE("GPL");